This invention relates to a method for producing analgesia or reducing hyperalgesia.
At the present time the common method for producing analgesia comprises administering an opiate such as morphine sulfate to the patient. While the opiates are highly effective in producing analgesia, there use is undesirable since they are addictive even when used sparingly. This disadvantage has promoted extensive research to identify alternative analgesics which are effective while being non-addictive.
It has been repeatedly demonstrated that reductions in brain serotonin produce hyperalgesia to painful stimuli in test animals. This effect is observed when serotonin reductions are accomplished by diet, or brain lesions. It also has been demonstrated that reversal of the hyperalgesia can be induced by administering through the animal brain serotonin or the amino acid precursors of serotonin, tryptophan or 5-hydroxytryptophan. These results have led to the conclusion that serotonin concentration in the brain has a direct or indirect effect on hyperalgesia and may have an effect on analgesia. However, it also has been demonstrated that the mere administration of brain serotonin or its amino acids precursors does not produce analgesia. Similarly, it has demonstrated that known compounds which inhibit serotonin uptake do not produce analgesia including chlorimipramine. Thus, for a composition to be an effective analgesic, it should have the effect of inhibiting uptake of serotonin as well as having additional effects which have not yet been identified.
It would be highly desirable to provide an otherwise innocous analgesic which could serve as a substitute for opiates in order to avoid the problems of addiction which accompany the administration of opiates.